CVE-2026-115774

MEDIUM 4.9

Twisted: Denial of Service in the Twisted IMAP4 Server via a Negative Literal Size in SEARCH

CVSS Score

4.9

EPSS Score

0.0%

EPSS Percentile

0th

Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.mail.imap4.IMAP4Server reaches twisted.mail.imap4.parseNestedParens with a negative literal size in an authenticated SEARCH command after the client enters the selected mailbox state. The negative size moves the parser cursor below zero, and Python's negative indexing prevents the synchronous scanning loop from terminating. The loop freezes the single-threaded reactor, stopping other IMAP connections and any SMTP or POP3 services hosted in the same process until restart. This issue is fixed in version 26.10.0rc1.

CWE	CWE-400 CWE-835
Vendor	twisted
Product	twisted
Published	Oct 23, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

twisted / twisted

< 26.10.0rc1

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/twisted/twisted/security/advisories/GHSA-2qrf-pqgx-qh9v github.com: https://github.com/twisted/twisted/pull/12764 github.com: https://github.com/twisted/twisted/commit/3d125548bcbe955007cb97f480bb699a5e074741 github.com: https://github.com/twisted/twisted/releases/tag/twisted-26.10.0rc1